question

tinka avatar image
tinka asked

MPPT 100/20 loss due to long cables to battery

I use a MPPT 100/20 with existing wiring to charge LFP batteries. The voltage drop from regulator to battery leads in a reduction of loading current because the MPPT measures the voltage at the regulator itself and not at the battery. But the MPPT knows the current on the cable and could compensate it. Is it possible to configure the device that it knows the resistance of the cable?

Is it possible to set the maximum current in balancing mode? I have 1A balancer but use 20A charging current in normal mode.

MPPT Controllers
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1 Answer
klim8skeptic avatar image
klim8skeptic answered ·

Some ideas.

1. Use short or thicker cables between controller and batteries.

2. Use a Smart battery sense/BMV 712, networked to your charge controller to negate voltage difference.

3. Wait a couple of months for the new features of Victron Connect to be available. (voltage offset between battery and CC)

"Is it possible to set the maximum current in balancing mode? I have 1A balancer but use 20A charging current in normal mode."

Dunno about this.

I threw my new unbalanced cells straight into service (not recommended). After a few charge cycles the balancers (and a light bulb shunt) top balanced the cells nicely. Top balancing really only occurs during the "absorb" charging phase when the charge current tapers off.

Seek further advice.

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